The auditory papilla of the Western Fence Lizard, Sceloporus occidentalis provides an excellent model for an analysis of the types, number, and distribution of nerve terminals on all of its 72 hair cells. Twelve of these hair cells are short-ciliated, unidirectionally oriented and centrally located. The other 60 hair cells are arranged in 2 rows of opposingly oriented long-ciliated hair cells, 3- apical and 30 basal to the central 12 cells. The number and size distribution of innervating fibers will be determined. The projection of all auditory fibers to specific posterior ganglion cells and cochlear nuclei will be determined. Methods of study will involve: (1) TEM study of the papillar nerve, (2) silver and histochemical techniques for fiber distribution within the papilla, (3) serial thick plastic sections of the papilla together with TEM corroboration of nerve ending morphology, (4) surgical section of different portions of the auditory (papillar) nerve with subsequent study to locate site of degenerating cell bodies in the posterior ganglion, (5) HRP injection of similar papillar nerve segments to corporate degeneration studies, (6) direct injection of HRP into auditory ganglion cells with subsequent observation of papillar cells and auditory nuclei marked by the HRP, thus determining exact connections of papillar segments with specific cochlear nuclear areas, (7) surgical section of central portions of papillar nerve close to the medulla and studying degeneration in the cochlear nuclei and changes in the associated posterior ganglion cells, (8) HRP injection of specific cochlear nuclei to corroborate surgical studies, and (9) H3-proline injection of superior olivary nucleus and subsequent autoradiographic study of papilla to determine if this nucleus is the site of papillar efferent fibers.